X-ray image sensors using a CCD instead of an X-ray sensitive film are becoming popular as a medical X-ray diagnostic apparatus. In such a radiation imaging system, a radiation detector having a plurality of pixels acquires two-dimensional image data by radiation as an electrical signal, and this signal is processed by a processor and displayed on a monitor. A typical radiation detector has a structure in which a scintillator is arranged on one- or two-dimensionally arranged photodetectors and incident radiation is converted into light by the scintillator to detect the light.
WO98/36291 discloses a radiation detector in which CsI is used as a scintillator material and a protective film made of parylene or the like is formed for hygroscopic prevention of the scintillator. This radiation detector has a structure in which a bonding pad is exposed from the protective film. The bonding pad and an external wiring line are connected to read an image signal.